It is often desirable to be able to detect the presence and location of small vessels on or in a body of water, for the purpose of protecting a harbor or other such facility, or for other purposes. In the vicinity of a typical harbor there is often an area of water having a moderate depth, in the range of one hundred to four hundred feet deep. This moderate depth water is often located in a strait, at the perimeter of, or just outside the harbor.
In order to protect such an area, the area of moderate depth water should be scanned by a detection system which can cover the area from essentially the surface of the water to the bottom. An irregular bottom should also be taken into consideration. Typically, such a body of water will lend itself to being divided into sectors. With currently known systems, it can be difficult to deploy a detection system specifically designed for the particular bottom contours and depths encountered. This often calls for specific engineering solutions to the various detection problems encountered. The configuration of the harbor drives the design of the sonar system. The systems thusly designed are usually unsuitable for other bodies of water and other harbors.
A fixed system can sometimes cost too much to be justified for a given harbor, if the threat is low, or if the amount of shipping does not justify the expense. However, even in such a low risk harbor, a period of heightened tension can give rise to the need to provide protective surveillance in a short period of time. Further, even for a given harbor, the risk against which protection is sought can change quickly. The reason for the change sometimes involves smaller or larger vessels than originally foreseen, or changing from a surface threat to a submarine threat. The risks can also change quickly if the number or types of ships in the harbor change materially. This can call for the temporary but rapid extension of the coverage of an existing system. It is often necessary to respond quickly to such changes in the risk scenario by installing or modifying a sonar system.
The ability to rapidly assemble a detection system and put it into operation can also be useful when a permanently installed detection system must be taken out of service temporarily for repairs. It can be beneficial to assemble a temporary system from modular components for use during repair of the permanent system. Finally, known systems are sometimes difficult to maintain because of their specialized design. Marine life can foul the equipment used, and the necessary removal, cleaning, and reinstallation of components can require significant down time. For this reason, modularity of the components of a sonar system could facilitate the maintenance of the system.
In light of the above, it is an object of the present invention to provide a modular system of active sonar platforms which can be quickly and easily configured to respond to a given risk scenario in a variety of depths and bottom contours by arranging a plurality of the platforms in any desired pattern. It is a further object of the present invention to provide a modular system of active sonar platforms, with each platform utilizing a plurality of modular transducer arrays which can be moved from one platform to another and from one position on the platform to another. It is a yet further object of the present invention to provide a surveillance system that is rapidly deployable, recoverable, and battery powered, with either a fiber optic link or a radio frequency link to a shore station. It is a still further object of the present invention to provide a modular surveillance system which is adaptable to changes in acoustic propagation conditions. Finally, it is an object of the present invention to provide a modular system of active sonar platforms which is easy and economical to assemble and operate.